CART - Compact Autonomous Robotic Transport for Porsche

Next generation robotic transport

CART is a Compact Autonomous Robotic Transport for the Porsche AGV Challenge, it was a joint winner. The challenge was to design an autonomous, robotic transport for moving assembled vehicles around the Porsche factory in Stuttgart. Parts of the factory are quite old and space is at a premium so a compact, maneuverable solution was required. Traditionally, finished cars were simply driven off the end of the assembly line for various testing procedures. This is no longer possible due to stricter health and safety requirements. Various automated guided vehicles (AGVs) are already commercially available, however they either can’t cater for extremely low sports cars, or those that can are too low to navigate the factory’s steep ramps. Current AGVs typically have a larger footprint than the largest vehicle they can carry, a major limitation for the Porsche factory’s narrow turns and corridors. The design intent was to create a solution that addressed all of these issues in a compact, reliable and cost effective package.

Bespoke factory solution

In order to overcome these challenges, a clean-sheet concept was required. The Compact Autonomous Robotic Transport (CART) exceeds every requirement put forward by the Porsche team. The most under served constraints were prioritised in order to produce a solution that cannot be fulfilled by existing AGVs. Specifically, minimising overall footprint and being able to lift vehicles with a ride height of 50mm while touching only the tyres to minimise the risk of damage.

small but strong

The most obvious innovation is the move to four miniature robots as opposed to a single large AGV. This grants a number of advantages. Each CART has a very compact footprint of 1032 x 878 x 320mm and only weighs 120kg. Yet they can work in teams of four to move a 3000kg vehicle up a 7.5° incline at up to 1m/s, like a team of ants. The mecanum wheels allow them to move in any direction, they can strafe like a crab, move diagonally or even turn on the spot, making them far more maneuverable than the vehicle they’re carrying.

Robots in disguise

The most difficult challenge to overcome was the ultra-low ride height requirement. In order to pick up a sports car by the tyres, the robot must first reach under it. CART has been designed to lift vehicles with ride heights as low as 50mm from the ground, considerably below Porsche’s requirements. For context, that’s around 25mm lower than the rear ride height of a Formula 1 car. CART achieves this by transforming into loading mode, this shifts the entire inner chassis to the same side as the outer chassis. It lowers the lifting fork to minimum height and then slides under the vehicle. CART then lifts the vehicle using the hydraulic lifting module, which adds 120mm to the ride height, allowing it to easily crest steep ramps. The inner chassis then slides back into transport mode and the CART team delivers the vehicle to its destination.

Porsche challenge winner

CART was selected as a winner of the Porsche Autonomous Factory Transport Challenge and Porsche subsequently purchased non-exclusive rights to produce it. CART was shortlisted for an IDI Award in 2020 in the Industrial Product category.

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